Zulfiqar Ahmad Bhatti

Low temperature conversion of plastic waste into light hydrocarbons.

Advance recycling through pyrolytic technology has the potential of being applied to the management of plastic waste (PW). For this purpose 1 l volume, energy efficient batch reactor was manufactured locally and tested for pyrolysis of waste plastic. The feedstock for reactor was 50 g waste polyethylene. The average yield of the pyrolytic oil, wax, pyrogas and char from pyrolysis of PW were 48.6, 40.7, 10.1 and 0.6%, respectively, at 275 degrees C with non-catalytic process. Using catalyst the average yields of pyrolytic oil, pyrogas, wax and residue (char) of 50 g of PW was 47.98, 35.43, 16.09 and 0.50%, respectively, at operating temperature of 250 degrees C. The designed reactor could work at low temperature in the absence of a catalyst to obtain similar products as for a catalytic process.

Anaerobic microbial fuel cell treating combined industrial wastewater: Correlation of electricity generation with pollutants.

Microbial fuel cell (MFC) is a new technology that not only generates energy but treats wastewater as well. A dual chamber MFC was operated under laboratory conditions. Wastewater samples from vegetable oil industries, metal works, glass and marble industries, chemical industries and combined industrial effluents were collected and each was treated for 98h in MFC. The treatment efficiency for COD in MFC was in range of 85-90% at hydraulic retention time (HRT) of 96h and had significant impact on wastewater treatment as well. The maximum voltage of 890mV was generated when vegetable oil industries discharge was treated with columbic efficiency of 5184.7C. The minimum voltage was produced by Glass House wastewater which was 520mV. There was positive significant co-relation between COD concentration and generated voltage. Further research should be focused on the organic contents of wastewater and various ionic species affecting voltage generation in MFC.

Combined industrial wastewater treatment in anaerobic bioreactor posttreated in constructed wetland.

Constructed wetland (CW) with monoculture of Arundo donax L. was investigated for the posttreatment of anaerobic bioreactor (ABR) treating combined industrial wastewater. Different dilutions of combined industrial wastewater (20, 40, 60, and 80) and original wastewater were fed into the ABR and then posttreated by the laboratory scale CW. The respective removal efficiencies of COD, BOD, TSS, nitrates, and ammonia were 80%, 78–82%, 91.7%, 88–92%, and 100% for original industrial wastewater treated in ABR. ABR was efficient in the removal of Ni, Pb, and Cd with removal efficiencies in the order of Cd (2.7%) > Ni (79%) > Pb (85%). Posttreatment of the ABR treated effluent was carried out in lab scale CW containing A. donax L. CW was effective in the removal of COD and various heavy metals present in ABR effluents. The posttreatment in CW resulted in reducing the metal concentrations to 1.95 mg/L, 0 mg/L, and 0.004 mg/L for Ni, Pb, and Cd which were within the permissible water quality standards for industrial effluents. The treatment strategy was effective and sustainable for the treatment of combined industrial wastewater.

Biological treatment of the dye Reactive Blue 19 by cattails and anaerobic bacterial consortia

This study demonstrates the bioremediation potential of anaerobic sludge and cattail (Typha angustifolia) for the treatment of the dye Reactive Blue 19 (RB19). The anaerobic sludge and cattails used in this study were not previously exposed to dyes or other xenobiotics. Different anaerobic sludge concentrations (30%, 50%, and 70%) were used along fixed dye concentrations at pH 8.0 and 25 °C. Subsequently, 50% sludge was selected to treat RB19 at various concentrations. The discoloration of non-hydrolyzed dye was between 70% and 85% using 50% biomass. For the hydrolyzed form of RB19, the range of decoloration was 70%–90%. Dye treatment efficiencies between 50% and 75% were observed for the two forms of the dye when treated with T. angustifolia. Overall, the anaerobic biomass at pH 8.0 showed better potential than cattails to treat RB19. The observation that non-enriched anaerobic sludge can decolorize RB19 is important because it opens up the prospects of developing anaerobic treatment systems, which can easily decolorize dyes in industrial wastewaters and also possesses potential advantages over systems using defined bacterial cultures.

Rendering plant emissions of volatile organic compounds during sterilization and cooking processes

The rendering process emits odorous volatile compounds in the atmosphere; if these volatile organic compounds (VOCs) are not handled properly they can cause a serious environmental problem. During this process not all emitted compounds are odorous and hazardous but some of them have been found associated with health problems. Samples were collected in the plastic bags from the Arnout rendering plant. In this study, VOCs emission from two different processes (cooking and sterilization) was compared. For the analysis of various emitted compounds, gas chromatograph and mass spectrophotometer were used. A sterilization process was added in the rendering plant to inactivate the prion protein from meat bone meal prepared during the rendering process. The identification of mass spectrum was performed by using a mass spectral database system. The most odorous classes of compounds identified were aliphatic hydrocarbons (HCs) (29.24%), furans (28.74%), aromatic HCs (18.32%), most important sulphur-containing compounds (12.15%), aldehyde (10.91%) and ketones (0.60%). Emissions released during cooking and sterilization were 32.73×102 and 36.85×102 mg m−3, respectively. In this study, it was observed that after the addition of the sterilization process VOCs’ emissions were increased. A total of 87 mg m−3 dimethyl disulphide (DMS) was detected only during the cooking process, whereas dimethly trisulphide (DMTS) was detected in both cooking (300 mg m−3) and sterilization (301 mg m−3) processes. About 11 mg m−3 of DMS was detected during the cooking process, which was a small concentration compared with 299 mg m−3 found during the sterilization process. At high temperature and pressure, DMTS and DMS were released more than any other sulphur-containing compounds. A condenser was applied to control the combined emission and it was successful in the reduction of VOCs to 22.83×102 mg m−3 (67% reduction).

Industrial wastewater treatment in internal circulation bioreactor followed by wetlands containing emergent plants and algae

Wastewater treatment based on ecological principles is a low cost and highly desirable solution for the developing countries like Pakistan. The present study evaluated the effectiveness of biological treatment systems including Internal Circulation (IC) anaerobic bioreactor and constructed wetlands (CWs) containing macrophytes and mixed algal cultures for industrial wastewater treatment. The IC bioreactor reduced COD (52%), turbidity (89%), EC (24%) of the industrial wastewater. However, the effluents of IC bioreactor did not comply with National Environmental Quality Standards (NEQS) of Pakistan. Post-treatment of IC bioreactor effluents was accomplished in CW containing macrophytes (Arundo donax and Eichhornia crassipes) and mixed algal culture. The CWs planted with macrophytes lowered the concentrations of COD (89%) and turbidity (99%). CWs with algal biomass were not effective in further polishing the effluent. Inhibition of algal biomass growth was observed due to physicochemical characteristics of wastewater. The integrated treatment system consisting of IC bioreactor and macrophytes was found more suitable option for industrial wastewater treatment.

Fungal strain Aspergillus flavus F3 as a potential candidate for the removal of lead (II) and chromium (VI) from contaminated soil

Abstract Metal contamination of soil is a serious environmental problem due to mining and use of synthetic products (e.g. pesticides, paints, batteries, and industrial wastes), which are serious threat to human life. The current research is aimed at the remediation of soil contaminated with lead (II) and chromium (VI) using indigenous fungal strains through the comparative study of bioleaching and chemical leaching methods. The removal efficiencies of Pb (II) and Cr (VI) in bioleaching were higher than chemical leaching, where 99% Cr (VI) and 36% Pb (II) were removed by Aspergillus flavus (F3) in bioleaching through the production of approximately 332 mg L-1 malic acid, 213 mg L-1 succinic acid, and 35 mg L-1 citric acid. The removal efficiencies in chemical leaching were 21.30% for Pb (II) and 1.92% for Cr (VI) by malic acid, 29.30% for Pb (II) and 72% for Cr (VI) by succinic acid, 22.21% for Pb (II) and 60.70% for Cr (VI) by citric acid, and 2.20% for Pb (II) and 2.47% for Cr (VI) by oxalic acid. The sequential extraction procedure for Pb (II) and Cr (VI) before and after bioleaching showed that Pb (II) and Cr (VI) mostly bound to stable fractions after bioleaching. Scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX) helped to identify the characteristic changes in the morphology and elemental composition of A. flavus (F3) biomass before and after bioleaching, whereas Fourier transform infrared spectroscopy (FTIR) showed that fungal biomass contain hydroxyl, carboxyl, fatty acids, and amine groups on its surface. The results implied that the fungal strain A. flavus (F3) can be used to remediate soils contaminated with Pb (II) and Cr (VI).